According to a report in the September 21 issue of JAMA, an examination of almost 30 investigations consisting of over 300,000 patients discovered that depression is linked with a considerably increased risk of developing stroke and stroke-related death.

"Stroke is a leading cause of death and permanent disability, with significant economic losses due to functional impairments. Depression is highly prevalent in the general population, and it is estimated that 5.8 percent of men and 9.5 percent of women will experience a depressive episode in a 12-month period. The lifetime incidence of depression has been estimated at more than 16 percent in the general population," according to data in the report. Although if depression raises the risk of stroke directly is not clear.

An Pan, Ph.D., of the Harvard School of Public Health, Boston, and colleagues carried out a systematic review and a meta-analysis of prospective cohort investigations to explain the connection between depression and risk of total and subtypes of stroke. A search of the medical literature was conducted by the investigators, in which 28 prospective cohort studies were identified that all met criteria for inclusion in the examination. The investigations, which consisted of 317,540 patients, revealed 8,478 stroke cases throughout a follow-up period that ranged from 2 to 29 years.

They discovered when information from the investigations were combined, the examination revealed that depression was linked with a increased risk of 45% for total stroke, a 55% increased risk for fatal stroke, and a 25% increased risk for ischemic stroke. Depression was not connected with an increased risk of hemorrhagic stroke.

Based on the most latest stroke statistics for the U.S., the equivalent total risk difference linked with depression was estimated to be, per 100,000 individuals each year, 106 cases for total stroke, 53 cases for ischemic stroke, and 22 cases for fatal stroke.

The investigators believe that depression might contribute to stroke through a wide range of factors, including having known neuroendocrine (relating to the nervous and endocrine systems) and immunological/inflammation effect, poor health behaviors (i.e., smoking, physical inactivity, poor diet, lack of medication compliance) and obesity, having other major comorbidities, such as diabetes and hypertension, both of which are huge risk factors for stroke, and antidepressant medication use, which might contribute to the observed connection.

"In conclusion, this meta-analysis provides strong evidence that depression is a significant risk factor for stroke. Given the high prevalence and incidence of depression and stroke in the general population, the observed association between depression and stroke has clinical and public health importance. More studies are needed to explore the underlying mechanisms and elucidate the causal pathways that link depression and stroke."